The Pacific Islands Forum's election observer team to Papua New Guinea says a large number people were deprived of their constitutional rights to vote during the past month's polling.
The team deployed from 19 June to 24 July, and observed pre-polling, polling, and counting.
In an interim statement released yesterday the observer group said there were several significant challenges noted, the most serious of which was the alarmingly large number of names missing from electoral rolls.
It said this was especially disappointing given the team observed high levels of civic awareness and interest in participating in the election.
Other issues noted included the absence of security personnel in some polling stations and the late deployment of security to some remote locations - both situations reportedly due to the late disbursement of funds.
There were also isolated incidences of discrepancies observed in procedures for polling, including assisted polling.
The Forum team said it realised most of the challenges observed in this year's election had been raised by previous election observer groups, in 2007 and 2012, particularly with regard to the electoral roll.
It said while there had been attempts by PNG to improve on aspects of the conduct of elections, the team was of the view that a more concerted and timely effort needed to be made to learn from experiences and prepare for future elections.
It said this should include timely support from the National Government to the Electoral Commission and relevant departments and agencies to help prepare for elections.
The full report from the Forum electoral observer team will be completed once counting is finishes and handed over to the Papua New Guinea government.